Clean backport of fix for bug where owned stage disappears when moved to another screen. This has baked in mainline for about 3 weeks and no problems have been observed. I verified that the fix works equally well on jfx25u.
------------- Commit messages: - 8252373: [macOS] Stage with owner disappears when moved to another screen Changes: https://git.openjdk.org/jfx25u/pull/35/files Webrev: https://webrevs.openjdk.org/?repo=jfx25u&pr=35&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8252373 Stats: 235 lines in 5 files changed: 207 ins; 9 del; 19 mod Patch: https://git.openjdk.org/jfx25u/pull/35.diff Fetch: git fetch https://git.openjdk.org/jfx25u.git pull/35/head:pull/35 PR: https://git.openjdk.org/jfx25u/pull/35
